Depletion of the world's petroleum reserves and increased concern for the environment are incentives for refiners to search for methods of reclaiming used lubricating oils.
The growing concern for environmental protection has prompted Congressional interest in mandating waste recycling laws. Used lubricating oils are among the wastes of interest. Proposed legislation has been directed towards implementing management standards for used oil recycling. The major focus of certain proposals has been to reintroduce used lubricants to the refinery process. Specific proposals include requiring refiners to recycle a yearly amount of used oil equal to a certain percentage of their total lubricant oil production, reintroduce the used oil into refinery processes for purposes of producing useable petroleum products and commence a credit system in which lubricant recyclers create credits for used lubricant recycling by actually recycling the oil through reintroduction to refinery processes or by purchasing recycling credits from recyclers in order to comply with the mandatory recycling percentage.
Even though the recycling of used lubricating oil by reintroduction into the refinery process has only been proposed, the refiner would benefit from the ability to recycle lubricating oils by reintroducing the oil into the refinery process. However, problems with reintroducing used oil to the refinery process are severalfold. Certain residual materials such as metals and lubricant additives in the lubricating oils present serious logistical problems to the refinery process. Problems include locating a process step which can accept used lubricating oils without the risks of fouling catalysts, contaminating process streams and causing coking and fouling of the process lines.
One approach would be to re-refine the oils to produce a lubricant stock. However, re-refining the used oils to produce base lubricant oil stocks is not a completely satisfactory approach because the known processes produce large quantities of sludge which present disposal problems. Morover, purification procedures required to pretreat the used oil are costly and can change the quality of the base oil resulting in a product of low quality.